Introduction:

Levers allow us to lift objects that are much heavier than we are. How is that possible?

Activity:

Visit three Lever Stations as directed by your teacher. Read the card, try the activity, and discuss the questions with your partners.

• In this station, pretend that a father and his young son want to play on the see-saw. Arrange the "father" weight and the "son" weight so they balance.
  • How did you have to arrange the two weights?
  • The father" weight is twice as heavy as the "son" weight. Is the "son" twice as far from the fulcrum?
  • Who moved more in this see-saw--"father" or "son"?
• In this station, please arrange the lever arm and fulcrum so that the alien toy can lift the brick.
  • How did you have to arrange everything?
  • Which was heavier--the alien or the brick?
  • Which moved farther--the alien or the brick?
• Try lifting the wooden plank just off the table, using one rubber band at a time.
  • Which rubber band stretched more?
  • Which was harder to pull?
  • Which required more force?
  • Now try lifting the wooden plank to a vertical position by gripping one eye-screw at a time.
    • Which one was harder to pull (at first)?
    • Which one made your fingers move farther?

Conclusion:

What do scientists mean by "FORCE-DISTANCE TRADEOFF"?

Enrichment:

Raising the Moai on Easter Island (Edited to <5 min.)
Entire Episode: